SAN DIEGO — Republican presidential candidate John McCain, in one of his strongest endorsements of free trade, called himself "an unapologetic supporter of NAFTA," an agreement that many Americans feel has cost them jobs.

"I reject the false virtues of economic isolationism," McCain told the National Council of La Raza, a major Hispanic organization. "Any confident, competent country and its government should embrace competition," he said. "It makes us stronger."

The Arizona senator has often defended free trade, but Monday's speech was among his most detailed and full-throated commentaries.

"Lowering barriers to trade creates more and better jobs, and higher wages," he said. "It makes goods more affordable for low- and middle-income consumers."

Citing his recent visit to Colombia and Mexico, McCain said he understands "how vitally important it is to the prosperity and security of our country to strengthen our trade, investment and diplomatic ties to other countries in our hemisphere." He said he fully supports the North American Free Trade Agreement, the Central American Free Trade Agreement and the Colombian Free Trade Agreement.

Congress approved NAFTA with Mexico and Canada in 1993, and the agreement with six Central American nations in 2005 but has blocked the agreement with Colombia.

"I believe a hemispheric free trade agreement is a worthy and necessary goal whose time has come," he said of a proposal he unveiled during the campaign.

Acknowledging that some Americans do lose jobs "to foreign competition," McCain said he has proposed "a comprehensive reform of our unemployment insurance and worker retraining programs."

"And for workers of a certain age who have lost a job that won't come back," he said, "if they move rapidly to a new job we'll help make up the difference in wages between their old job and the new one."

McCain's Democratic opponent, Barack Obama, has been much cooler to free trade agreements and wants to revisit some aspects of NAFTA.

McCain said he has earned the trust of Hispanic voters by championing an immigration reform bill that nearly killed his presidential bid. Obama, he said, failed to take a similar stand on the politically explosive issue of illegal immigration.

Obama has criticized McCain for turning against his own immigration bill.

Reminding the group that Congress failed twice in the past three years to overhaul the nation's immigration laws, McCain said he did not want to try a third time until the government can "prove we have the resources to secure our borders and use them."

At the beginning of his speech, a heckler who yelled to stop the war and to bring home the troops. McCain paused and resumed speaking after the heckler and another woman were removed from the ballroom. He also took five questions from the audience, including three on the subject of immigration.

In his remarks, McCain said the two failed bills, which he supported, would have dealt "practically and humanely" with illegal immigrants "without excusing the fact they came here illegally or granting them privileges before those who have been waiting their turn outside the country."

Critics of the 2006 bill he backed, however, said it would have granted just such privileges to some illegal immigrants. It would have allowed those who have been in the country five years or more to remain, continue working and eventually become legal permanent residents and citizens after paying at least $3,250 in fines and fees and back taxes and learning English.

Obama told the La Raza gathering Sunday that he supports up to a 50 percent tax credit for small businesses providing health insurance to their employees, a program he hopes has special appeal to Hispanics and other minority groups struggling for a toehold in the U.S. economy.

In related news:

• Seventy-two percent of Americans say McCain would be a strong commander-in-chief compared with 48 percent who say Obama would be, according to an ABC News/Washington Post poll.

Americans were divided almost evenly on which of the presumptive presidential nominees they trust to handle Iraq: Obama got 45 percent support among 1,119 adults surveyed between July 10 and July 13, compared with 47 percent for McCain.

The poll — which ABC said had a 3 percentage point margin of error and was weighted with 209 black respondents to ensure a sample representative of the U.S. population — also found respondents divided on whether there should be a timetable for withdrawal from Iraq, as Obama has proposed.

Fifty percent favored Obama's plan to withdraw most forces within 16 months of the next president's inauguration, and 49 percent preferred no timetable, which McCain has advocated, saying events in Iraq should drive the decision.

Contributing: Bloomberg News